I used to use them as a kid also. In the hot summer we would collect them and catch gigantic (to me) bluegills in Womack Lake - between McMinnville and Manchester. The worm "pods" would be located in mature Ragweeds. Cut out the pods, put them in a bucket and go fishing. Here is the best description of using/finding them that I have seen:
http://willowhavenoutdoor.com/genera...-fishing-bait/
I have found a few of them here on our farm in Mt Juliet but they are relatively few and far between.